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Barnidge D, Troske D, North S, Wallis G, Perkins M, Harding S. Endogenous monoclonal immunoglobulins analyzed using the EXENT® solution and LC-MS. J Mass Spectrom Adv Clin Lab 2024; 32:31-40. [PMID: 38405412 PMCID: PMC10891330 DOI: 10.1016/j.jmsacl.2024.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 02/02/2024] [Accepted: 02/05/2024] [Indexed: 02/27/2024] Open
Abstract
Introduction The EXENT® Solution, a fully automated system, is a recent advancement for identifying and quantifying monoclonal immunoglobulins in serum. It combines immunoprecipitation with MALDI-TOF mass spectrometry. Compared to gel-based methods, like SPEP and IFE, it has demonstrated the ability to detect monoclonal immunoglobulins in serum at lower levels. In this study, samples that tested negative using EXENT® were reflexed to LC-MS to determine if the more sensitive LC-MS method could identify monoclonal immunoglobulins missed by EXENT®. Objectives To assess whether monoclonal immunoglobulins that are not detected by EXENT® can be detected by LC-MS using a low flow LC system coupled to a Q-TOF mass spectrometer. Methods Samples obtained from patients confirmed to have multiple myeloma (MM) were diluted with pooled polyclonal human serum and analyzed using EXENT®. If a specific monoclonal immunoglobulin was not detected by EXENT®, the sample was then subjected to analysis by LC-MS. For the LC-MS analysis, the sample eluate, obtained after the MALDI-TOF MS spotting step, was collected and transferred to an autosampler tray for subsequent analysis using LC-MS. Conclusion LC-MS has the capability to detect monoclonal immunoglobulins that are no longer detected by EXENT®. Reflexing samples to LC-MS for analysis does not involve additional sample handling, allowing for a faster time-to-result compared to current approaches, such as Next-Generation Sequencing, Next-Generation Flow, and clonotypic peptide methods. Notably, LC-MS offers equivalent sensitivity in detecting these specific monoclonal immunoglobulins.
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Affiliation(s)
- David Barnidge
- The Binding Site, Part of ThermoFisher Scientific Research and Development Laboratory, 3777 40th Ave NW, Rochester, MN 55906, United States
| | - Derek Troske
- The Binding Site, Part of ThermoFisher Scientific Research and Development Laboratory, 3777 40th Ave NW, Rochester, MN 55906, United States
| | - Simon North
- The Binding Site, Part of ThermoFisher Scientific, The Binding Site Group Ltd, 8 Calthorpe Road Edgbaston, Birmingham, UK
| | - Gregg Wallis
- The Binding Site, Part of ThermoFisher Scientific, The Binding Site Group Ltd, 8 Calthorpe Road Edgbaston, Birmingham, UK
| | - Mark Perkins
- The Binding Site, Part of ThermoFisher Scientific, The Binding Site Group Ltd, 8 Calthorpe Road Edgbaston, Birmingham, UK
| | - Stephen Harding
- The Binding Site, Part of ThermoFisher Scientific, The Binding Site Group Ltd, 8 Calthorpe Road Edgbaston, Birmingham, UK
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OUP accepted manuscript. Clin Chem 2022; 68:1134-1150. [DOI: 10.1093/clinchem/hvac061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 03/04/2022] [Indexed: 11/13/2022]
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Csako G. Isoelectric Focusing in Agarose Gel for Detection of Oligoclonal Bands in Cerebrospinal and Other Biological Fluids. Methods Mol Biol 2019; 1855:387-401. [PMID: 30426434 DOI: 10.1007/978-1-4939-8793-1_33] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Isoelectric focusing (IEF) coupled with immunodetection (immunofixation or immunoblotting) has become the leading technique for the detection and study of oligoclonal bands (OCBs) in cerebrospinal fluid (CSF) and also is increasingly used in other body fluids such as the tear and serum. Limited commercial availability of precast agarose IEF gels for research and a need for customization prompted reporting a detailed general protocol for the preparation and casting of agarose IEF gel along with sample, control, and isoelectric point marker preparation and carrying out the focusing itself for CSF OCBs. However, the method is readily adaptable to the use of other body fluid specimens and, possibly, research specimens such as culture fluids as well.
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Affiliation(s)
- Gyorgy Csako
- Department of Laboratory Medicine, Clinical Center, National Institutes of Health, Bethesda, MD, USA.
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He L, Anderson LC, Barnidge DR, Murray DL, Hendrickson CL, Marshall AG. Analysis of Monoclonal Antibodies in Human Serum as a Model for Clinical Monoclonal Gammopathy by Use of 21 Tesla FT-ICR Top-Down and Middle-Down MS/MS. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:827-838. [PMID: 28247297 DOI: 10.1007/s13361-017-1602-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 01/07/2017] [Accepted: 01/11/2017] [Indexed: 05/27/2023]
Abstract
With the rapid growth of therapeutic monoclonal antibodies (mAbs), stringent quality control is needed to ensure clinical safety and efficacy. Monoclonal antibody primary sequence and post-translational modifications (PTM) are conventionally analyzed with labor-intensive, bottom-up tandem mass spectrometry (MS/MS), which is limited by incomplete peptide sequence coverage and introduction of artifacts during the lengthy analysis procedure. Here, we describe top-down and middle-down approaches with the advantages of fast sample preparation with minimal artifacts, ultrahigh mass accuracy, and extensive residue cleavages by use of 21 tesla FT-ICR MS/MS. The ultrahigh mass accuracy yields an RMS error of 0.2-0.4 ppm for antibody light chain, heavy chain, heavy chain Fc/2, and Fd subunits. The corresponding sequence coverages are 81%, 38%, 72%, and 65% with MS/MS RMS error ~4 ppm. Extension to a monoclonal antibody in human serum as a monoclonal gammopathy model yielded 53% sequence coverage from two nano-LC MS/MS runs. A blind analysis of five therapeutic monoclonal antibodies at clinically relevant concentrations in human serum resulted in correct identification of all five antibodies. Nano-LC 21 T FT-ICR MS/MS provides nonpareil mass resolution, mass accuracy, and sequence coverage for mAbs, and sets a benchmark for MS/MS analysis of multiple mAbs in serum. This is the first time that extensive cleavages for both variable and constant regions have been achieved for mAbs in a human serum background. Graphical Abstract ᅟ.
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Affiliation(s)
- Lidong He
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, 32310, USA
| | - Lissa C Anderson
- National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Dr., Tallahassee, FL, 32310, USA
| | - David R Barnidge
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, 55905, USA
| | - David L Murray
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Christopher L Hendrickson
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, 32310, USA
- National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Dr., Tallahassee, FL, 32310, USA
| | - Alan G Marshall
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, 32310, USA.
- National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Dr., Tallahassee, FL, 32310, USA.
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Abstract
Although mass spectrometry has been used clinically for decades, the advent of immunoassay technology moved the clinical laboratory to more labor saving automated platforms requiring little if any sample preparation. It became clear, however, that immunoassays lacked sufficient sensitivity and specificity necessary for measurement of certain analytes or for measurement of analytes in specific patient populations. This limitation prompted clinical laboratories to revisit mass spectrometry which could additionally be used to develop assays for which there was no commercial source. In this chapter, the clinical applications of mass spectrometry in therapeutic drug monitoring, toxicology, and steroid hormone analysis will be reviewed. Technologic advances and new clinical applications will also be discussed.
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Affiliation(s)
- D French
- University of California San Francisco, San Francisco, CA, United States.
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Mahmood S, Wassef NL, Salter SJ, Sachchithanantham S, Lane T, Foard D, Whelan CJ, Lachmann HJ, Gillmore JD, Hawkins PN, Wechalekar AD. Comparison of Free Light Chain Assays: Freelite and N Latex in Diagnosis, Monitoring, and Predicting Survival in Light Chain Amyloidosis. Am J Clin Pathol 2016; 146:78-85. [PMID: 27353767 DOI: 10.1093/ajcp/aqw079] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES Measurement of serum free light chains (FLCs) is critical in diagnosis, prognosis, and monitoring treatment responses in light chain (AL) amyloidosis. We compare the Freelite assay (polyclonal antibodies to hidden light chain epitopes), which is the current gold standard, with a new assay: a mixture of monoclonal antibodies to light chain epitopes (N Latex). METHODS We collected 240 serum samples from 94 consecutive patients with newly diagnosed AL amyloidosis (at least three serial serum samples during the first 6 months) analyzed at the National Amyloidosis Centre, London, from January 2011 to April 2012. Concordance in detecting abnormal light chain components and hematologic response was assessed at 2, 4, and 6 months. RESULTS The κ and λ clonal light chain involvement was 21% and 79%, respectively, with an abnormal κ/λ ratio or detectable protein in 78.7%. Median κ, λ, and difference in involved and uninvolved FLCs by Freelite and N Latex assays were 17.3 vs 16 mg/L (R(2 ) = 0.91), 48.8 vs 52.6 mg/L (R(2) = 0.52), and 43.2 vs 39.1 mg/L, respectively. Discordant κ/λ ratios at presentation were as follows: 10 of 90 abnormal by Freelite/normal by N Latex and 11 of 90 abnormal by N Latex/normal by Freelite. CONCLUSIONS Both FLC assays show good correlation in detecting the abnormal light chain subtype with discordance in absolute values and thus are not interchangeable.
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Affiliation(s)
- Shameem Mahmood
- From the National Amyloidosis Centre, University College London Medical School, Royal Free Hospital Campus, London, United Kingdom
| | - Nancy L Wassef
- Clinical Biochemistry Department, Royal Free London Foundation Trust, London, United Kingdom
| | - Simon J Salter
- Clinical Biochemistry Department, Royal Free London Foundation Trust, London, United Kingdom
| | - Sajitha Sachchithanantham
- From the National Amyloidosis Centre, University College London Medical School, Royal Free Hospital Campus, London, United Kingdom
| | - T Lane
- From the National Amyloidosis Centre, University College London Medical School, Royal Free Hospital Campus, London, United Kingdom
| | - D Foard
- From the National Amyloidosis Centre, University College London Medical School, Royal Free Hospital Campus, London, United Kingdom
| | - Carol J Whelan
- From the National Amyloidosis Centre, University College London Medical School, Royal Free Hospital Campus, London, United Kingdom
| | - Helen J Lachmann
- From the National Amyloidosis Centre, University College London Medical School, Royal Free Hospital Campus, London, United Kingdom
| | - Julian D Gillmore
- From the National Amyloidosis Centre, University College London Medical School, Royal Free Hospital Campus, London, United Kingdom
| | - Philip N Hawkins
- From the National Amyloidosis Centre, University College London Medical School, Royal Free Hospital Campus, London, United Kingdom
| | - Ashutosh D Wechalekar
- From the National Amyloidosis Centre, University College London Medical School, Royal Free Hospital Campus, London, United Kingdom
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